Conventionally, in an electronic piano, electronic sound is issued from a loudspeaker, in response to an player's depressing or releasing a key or keys. Recently, such electronic sound was improved to reach a highly desirable level. The feel of the keys on the electronic keyboard has also been improved in various ways, in order to reach the feel of the keys of an acoustic piano.
Specifically, an electronic piano provided with an action load simulation member is developed, such that the touch of the keys approaches the touch of the keys of an acoustic upright piano. As shown in FIG. 9, such electronic piano is provided with a hammer arm P14 rotatable about a shaft P10 for depressing the rear end of a key P12. As shown in FIG. 10, another electronic piano is provided with a hammer arm P20 rotatable about a shaft P16 for pushing up a key P18, such that the tip of the key 18 is raised (refer to the Japanese Patent Application laid-open No.4-347895). The action load simulation members shown in FIGS. 9 and 10 are developed for use in an electronic upright piano, having a low roof top height, such that almost acoustic piano sound can be generated.
The key touch on the acoustic upright piano is now explained. As shown in FIG. 11, when a player depresses a key 111, a wippen 115 is rotated in the direction opposite to the rotary direction of the key 111 (counterclockwise as viewed in the figure) and is raised, and a jack 117, rotatably attached to the wippen 115, is raised to push up a hammer butt 118. The hammer butt 118 is in turn rotated together with a hammer shank 121 and a hammer head 123 in the direction opposite to the rotary direction of the key 111 (counterclockwise as viewed in the figure). The jack 117 is raised to a predetermined position where a jack tail 117a contacts the bottom of a regulating button 116, and is then released from the hammer butt 118. Consequently, the hammer butt 118, the hammer shank 121 and the hammer head 123 continued to be inertially rotated, thereby striking a string.
As aforementioned, in the acoustic upright piano, the wippen 115, the jack 117 and the hammer butt 118 are rotated about different axes, respectively. In addition, the jack 117 leaves the hammer butt 118 at a specified timing. The touch of the key 111 is complicated.
However, in the action load simulation member shown in FIG. 9 or FIG. 10, a dead weight is rotated about an axis. Therefore, the key touch is simpler as compared with the key touch of the acoustic upright piano.